Nanoflower Structure Research Articles

Abnormal p‐type Gas‐Sensing Response to Ether in Co‐ZnO Nanocomposite Film and Its Significant Room‐Temperature Magnetoresistance

AbstractAs a remarkable gas‐sensing material, ZnO is limited by the gas selectivity of its indiscriminate response to multiple gases. Herein, abnormal p‐type responses to ether but n‐type responses to othervolatile organic compoundsare observed in Co‐ZnO nanocomposite films. It should be attributed to the p‐type inversion region at the ZnO particle interface, on which ether tends to selectively adsorb. By controlling Co content, a nanoflower structure is realized, which significantly increases the adsorption sites and enhances the abnormal p‐type response to eight times that of ZnO film. Dual‐mode output based on chemiresistive and magnetoresistance responses offers another way to improve gas selectivity. To this point, a dual‐response structure of Co‐ZnO nanocomposite granular film is constructed with superficial Co3O4‐ZnO p‐n heterojunction and internal Co‐ZnO superparamagnetic conduction path. The high saturation magnetization of 2990 Gs is realized in Co‐ZnO film with 26 at.% Co. P‐type gas‐sensing resistance variation of 12% and room‐temperature magnetoresistance of ‐7% are simultaneously achieved.

Modulation of oxygen vacancies in NiFe layered double hydroxides through dual-doping with Mo/Cr cations for efficient seawater hydrogen production

Seawater splitting to produce hydrogen holds promise for renewable energy but faces challenges from chloride ions, causing electrode corrosion and competition between chlorine oxidation reaction (ClOR) and oxygen evolution reaction (OER). Therefore, it is crucial to develop highly efficient and stable electrocatalysts for seawater splitting. Here, we employ a dual-doping strategy of Mo/Cr cations and a sulfuration approach to fabricate the S-MoCr-NiFe@NF bifunctional catalyst with a 3D nano-flower structure. The S-MoCr-NiFe@NF catalyst exhibits remarkable catalytic performance for the oxygen evolution reaction (OER) in 1.0 M KOH + 0.5 M NaCl and 1.0 M KOH + Seawater, achieving current densities of 10 mA cm−2 at low overpotentials of 116 and 141 mV, respectively. Furthermore, it was demonstrated that the S-MoCr-NiFe@NF catalyst exhibited remarkable performance in alkaline overall seawater splitting, requiring only 1.48 and 1.57 V to achieve current densities of 10 mA cm−2 in 1.0 M KOH + 0.5 M NaCl and 1.0 M KOH + Seawater, respectively. The in-situ Raman and DFT calculations confirm Ni as the primary active sites, reducing the energy barrier of the rate-determining step and enhancing OER performance. This study will offer a viable approach to developing and creating highly effective bifunctional catalysts for seawater splitting.

Application and performance Enhancement of acetic acid-Regulated ligand defect engineering in NiMOF electrocatalysts

Introducing organic ligands into metal-organic frameworks (MOFs) is an effective method for preparing defective MOFs. This approach enables the fabrication of cost-effective, efficient, highly conductive, and richly active-site electrocatalysts. Herein, the defective NiMOF is synthesized via a straightforward one-pot solvothermal method by partially substituting phthalic acid (PTA) ligands with acetic acid (HOAc), which effectively regulates the micro-morphology and electronic structure of the NiMOF nanoflowers, thus creating abundant electrochemical active sites, significantly improving electronic conductivity and promoting rapid charge transfer. The resulting DE-NiMOF-0.5 nanoflowers, prepared with HOAc substitution, demonstrate excellent electrochemical performance at a current density of 10 mA cm−2, the hydrogen evolution reaction (HER) overpotential is 188 mV (Tafel slope of 175 mV dec−1), while the oxygen evolution reaction (OER) overpotential is 205 mV (Tafel slope of 37 mV dec−1). The introduction of acetic acid ligands in DE-NiMOF-0.5 not only constructs the ligand defects within the catalyst, but also increases the abundant active sites, enhancing the hydrophilicity of the catalyst and facilitating electronic transfer between the catalyst surface and the electrolyte. This study explores a strategy for preparing defective MOF catalysts through introducing modulators, providing an economically viable material pathway for electrocatalysis and opening new possibilities for designing and synthesizing efficient electrocatalysts in future research endeavors.

Role of synthetic process parameters of nano-sized cobalt/nickel oxide in controlling their structural characteristics and electrochemical energy performance as supercapacitor electrodes

The synthesis of nano-sized bimetallic Cobalt/Nickel oxides (Ni1.5Co1.5O4) with a 1:1 Co/Ni atomic ratio has been achieved using a surfactant-free co-precipitation/hydrothermal process. The growth mechanism of Cobalt/Nickel oxides Ni1.5Co1.5O4 is elucidated by tuning the synthesis process parameters, including co-precipitation pH and hydrothermal time. The formation of Cobalt/Nickel oxides Ni1.5Co1.5O4 oxide began with the nucleation of cobalt nickel hydroxide nanoplates through the co-precipitation process, followed by dissolution-recrystallization, stacked hexagonal nano-flakes, and a flower-like microstructure. The electrochemical performances of the oxides were evaluated, with the largest surface area observed at pH 9 being the main factor for the best super-capacitive performance. As hydrothermal time increased, the structural directing growth forward, resulted in the formation of a nano-flower structure with a larger surface area. The as-prepared cobalt nickel oxide exhibited a maximum specific capacitance value of 525.5 F g-1 at a current density of 1 A g-1 and energy and power densities of 88.2 WhKg-1 and 606 WKg-1, respectively.

Flexible CoNiZn@Ti3CNTx MXene@carbon fabrics with hierarchical structure for efficient electromagnetic wave absorption

The widespread application of 5G technology has significantly exacerbated concerns regarding electromagnetic radiation. However, the rigidity and lack of flexibility of traditional electromagnetic wave (EMW) absorption materials make them ill-suited for protecting humans and certain specialized, complex shapes of equipment. Therefore, there is an increasing urgency to develop flexible EMW absorbing fabrics to effectively mitigate electromagnetic pollution. In this study, hierarchical structure CoNiZn@Ti3CNTx MXene@carbon fabrics (CoNiZn@Ti3CNTx@CF) were constructed from nano-flower structure CoNiZn-MOF, Ti3CNTx MXene and fabrics by self-assembly, in-situ growth and pyrolysis. The carbon fabric acts as a skeleton to form a 3D interconnected conductive network, in which loaded nano-flower structure CoNiZn@Ti3CNTx MXene (CoNiZn@Ti3CNTx@C) composites exists excellent dielectric loss and magnetic loss, so that EMW enters the fabric and optimizes the impedance matching, increasing the multiple reflection and scattering of EMW, thereby effectively attenuating EMW. The minimum reflection loss (RLmin) of CoNiZn@Ti3CNTx@CF reaches -44.51 dB at 14.88 GHz with filling ratio of 15 % and thickness of 1.50 mm and the effective absorption bandwidth (EAB) of CoNiZn@Ti3CNTx@CF reaches 4.32 GHz (13.04–17.36 GHz) at 1.55 mm. The EAB of CoNiZn@Ti3CNTx@CF is expanded to 14.56 GHz (3.44–18.00 GHz) through thickness adjustment (1–5.50 mm), covering most of the S, C, X, and Ku bands. The radar cross-section (RCS) value of CoNiZn@Ti3CNTx@CF is 17.3 dB m2 lower than the perfect electrical conductor (PEC), which effectively reduces the probability of the target being detected by the radar detector. This work provides ideas for design and development of flexible EMW absorbing materials.

Combustion Characteristics and Performance of Nanoflower Structure AlB2@AP Energetic Composites

ABSTRACT Boron-based solids have garnered significant attention due to their high calorific value. However, during combustion, the formation of boron oxide (B₂O₃) on the surface hinders the interaction between the oxidizing components and the internal active boron (B), thereby limiting its reactivity and combustion efficiency. Modifying boron-based solids represents an effective strategy for overcoming the limitations associated with fuel energy release efficiency. In this study, a shell-structured AlB₂@AP composite was designed and fabricated utilizing etching and recrystallization methods. The structure comprises AlB₂ as the core, B as the middle shell, and AP as the embedded outer shell. The key strategy involves employing an etching process to augment the reactive surface area of boron on the aluminum diboride surface, while also coating it with ammonium perchlorate (AP) to enhance the composite particles. This innovative approach demonstrates that the etching method can effectively utilize the boron present in AlB₂. The composite particles were characterized and analyzed for morphology employing a scanning electron microscope and X-ray techniques. Thermal analysis indicated that the decomposition stage of AP facilitated the oxidation of etched AlB₂, moreover, as the AP coating content increased, the temperature at which vigorous reactions initiated occurred earlier. In combustion experiments, the maximum combustion temperatures of AlB₂@10AP, AlB₂@20AP, and AlB₂@30AP increased by 36.4%, 15.1%, and 3.8%, respectively. The combustion formulation prepared with elemental boron exhibited different characteristics. The average combustion temperatures increased by 33.1%, 23.4%, and 14.4%, respectively. The combustion durations were reduced by 60.8%, 33.7%, and 31.7%, respectively. AlB2@AP is anticipated to further enhance its applications in propellants, explosives, and pyrotechnics.

Performance study of bimetallic Mn-Zn porous flower-like nanosheets as supercapacitor positive electrode materials

As environmental and carbon emission issues become increasingly severe, electrochemical energy storage systems have gained attention. Compared to traditional supercapacitors, zinc-ion hybrid capacitors (ZIHCs) are not only environmentally friendly but also cost-effective. MnO2, with its low cost, eco-friendliness, high theoretical capacity, and stable crystal structure, is considered a promising positive electrode material. In this study, the morphology of MnO2 was optimized using electrodeposition. During cycling, zinc ions reversibly intercalate and extract from MnO2, forming a cactus-like nanoflower structure. This structure is loose and porous, providing ample reaction space for active materials. The assembled device exhibits excellent performance in both energy density (85.68 Wh kg−1) and stability (91.60 %).

Copper ions coordination-promoted self-assembly of DNA nanoflowers as cascade catalytic nanoreactor for colorimetric biosensor

The controllable geometry and multifunctionality of DNA nano-bioreactors hold immense promise for disease diagnosis. Herein, a facile rolling circle amplification (RCA)-based crystallization method has been developed for highly efficient self-assembly of three-dimensional (3D) DNA nano-bioreactors, which show excellent cascade catalytic performance by confining bio-enzyme (glucose oxidase (GOx) used in this case) and copper ions (Cu2+) in DNA nanoflowers (DNFs) structure. The participation of Cu2+ during the self-assembly process not only endows the nano-bioreactors (designated as GOx/Cu@DNFs) with inspiring peroxidase-like activity but also greatly improves the assembly efficiency and yield via the effective coordination between Cu2+ and RCA-generated long concatemeric DNAs. The integration of GOx and Cu2+ in the constrained flower-like DNA nanomatrices makes for the efficient inter-catalyst communication, resulting in the striking enhancement of biocatalytic cascade activity. Based on the prepared nano-bioreactors, a colorimetric biosensor has been constructed for glucose detection, achieving a wide linear range (2–400 μM) and a low detection limit (0.45 μM). Furthermore, the proposed sensing strategy enables the accurate determination and discrimination of glucose levels in healthy and diabetic sera, delivering gratifying outcomes. Overall, the meticulously crafted cascade nano-bioreactors not only illuminate the design of multifunctional nanomaterials based on RCA, but also expand the conceptual framework of the universal analytical method for determining small molecules with catalytic reactions to generate H2O2.

NiMOF-Derived MoSe2/NiSe Hollow Nanoflower Structures as Electrocatalysts for Hydrogen Evolution Reaction in Alkaline Medium.

Metal-organic frameworks (MOFs) are crystalline porous materials for storage and energy conversion applications with three-dimensional pore structure, high porosity, and specific surface area, which are widely utilized in electrocatalysis. Herein, MoSe2/NiSe composites were synthesized by selenization reaction using NiMOF as the precursor. The composites were hollow nanoflower structures with a synergistic effect between MoSe2 and NiSe to promote rapid electron transfer, which exhibited good hydrogen evolution reaction performance in an alkaline medium. At a current density of 10 mA/cm2, the HER overpotential reaches 80 mV, the Tafel slope is 33.86 mV/dec, and the material has good stability, with polarization curves remaining essentially unchanged after 3000 cycles. These results indicate that the method has a promising application in the preparation of efficient and sustainable catalysts for hydrogen production in alkaline medium.

Hydrothermal Synthesis of ZnO Nanoflowers: Exploring the Relationship between Morphology, Defects, and Photocatalytic Activity

Two forms of flower-like ZnO nanostructures were synthesized using hydrothermal methods at various growth times/temperatures and zinc precursors. The morphology, structure, chemical composition, and optical properties of these ZnO nanoflowers were studied using a scanning electron microscope (SEM), X-ray diffraction spectroscopy (XRD), X-ray photoelectrons spectroscopy (XPS), Raman spectroscopy, and UV–Vis spectroscopy. The SEM images revealed two forms of flower-like nanostructures, namely lotus- and tulip-like flower ZnO nanostructures. The XPS analysis revealed the oxidation state of the Zn and O elements, as well as the presence of OH groups on the surface of the lotus-like flower ZnO nanostructure. The XRD results revealed less crystallinity of the lotus-like ZnO nanoflowers (NFs) compared with the tulip-like ZnO NFs. The XRD results revealed the presence of Zn (OH)2 in the ZnO NFs. The Raman results confirmed less crystallinity of the lotus-like ZnO NFs. The estimated optical bandgap was 2.92 and 3.0 eV for the tulip- and lotus-like ZnO NFs, respectively. The tulip-like ZnO NFs showed superior photocatalytic degradation of methylene blue dye, verified via UV–Vis radiation, compared with the lotus-like ZnO NFs, which show the impact of the structure defects and OH- impurities on the photocatalytic performance of ZnO nanoflowers.

Stratified nanoflower bimetallic cobalt/iron alloy derived from CoFe-MOFs as efficient peroxymonosulfate activator for antibiotics degradation: Performance, mechanism, and toxicity

Co-based metal-organic framework (Co-MOFs) derivative has gained wide attention in the field of advanced oxidative processes (AOPs). However, the degradation efficiency of single cobalt element remains suboptimal and its activation mechanism still needs to be further explored. In this study, stratified nanoflower bimetallic cobalt/iron alloys (CoFe-NC), derived from cobalt/iron bimetallic-organic frameworks (CoFe-MOFs), was synthesized via self-assembly at room temperature, hydrothermal synthesis and high-temperature carbonization processes and their performance as efficient activators of peroxymonosulfate (PMS) for the degradation of antibiotics was evaluated (removal efficiency of 100 % within 40 min, k=0.0951 min−1). The excellent degradation property benefit by specific nano-flowers structure with high specific surface area (424.67 m2/g), the cycle between Co0→Co2+↔ Co3+ and Fe0→Fe2+↔Fe3+, synergistic effect of Co and Fe bimetals. Furthermore, the CoFe-NC/PMS system exhibits exceptionally high cyclic stability (over 85 % degradation efficiency after four times degradation), a wide range of pH (3−11) and resistance to background ion interference (Cl–, H2PO4–, NO3–, HCO3– and HA), and reduced toxicity of the degradation products. Degradation mechanistic studies demonstrated that the activation of PMS by CoFe-NC generated amounts of reactive oxygen species (ROS) (SO4•−, •OH, •O2− and 1O2). Additionally, high-performance liquid chromatography-mass spectrometry (HPLC-MS) analysis identified fifteen intermediate degradation products and three possible degradation pathways were proposed. The results highlight the potential of CoFe-NC as a catalyst for antibiotic removal, providing insights into the optimization of bimetallic-organic framework for environmental applications.

Flower-like ZnO/BiOI p–n heterojunction composite membrane composed of nanosheets for enhanced photodegradation of water-soluble pollutant and high efficiency oil–water emulsion separation

The emulsified oil wastewater produced from the petrochemical industries and people’s daily life would cause severe harm to the ecological environment if improperly treated. Thus, the development of membranes with efficient oil–water separation and self-cleaning property remains a key global research direction. In this study, p-n heterojunctions membrane with BiOI@ZnO hierarchical flower-like-nanosheets structures (BiOI@ZnO@SSM) has been successfully fabricated through two-step electrodeposition method. The BiOI@ZnO@SSM is capable of separating water and oil from emulsified oil wastewater and performing efficient adsorption and photocatalytic degradation of organic pollutants in water. The separation efficiency of BiOI@ZnO@SSM for numerous oil-in-water (O/W) emulsions exceeded 99.3 % as well as a fast permission flux up to 299.8 L·m−2·h−1. And the degradation efficiency of BiOI@ZnO@SSM for Rhodamine B (RhB) can reach to 99.0 % in 80 min under visible-light irradiation, which is 1.5 times as high as that of ZnO@SSM. The obviously enhanced photocatalytic activity of BiOI@ZnO@SSM is due to the formation of p-n heterojunction between p-type BiOI and n-type ZnO, which broadens the light absorption range, promotes the effective separation and prolongs the lifetime of electron and hole pair and realizes efficient degradation of organic pollutants. Meanwhile, multidimensional and hierarchical nanoflowers structure is not only helpful to improve the utilization of light, but also can increase more catalytic active sites. After ten cycles, this membrane maintained high emulsion separation efficiency of 99.6 % and the photodegradation efficiency remained above 94.5 %, demonstrating its good recyclability and stability. This durable and multifunctional heterojunction composite membrane with a flower-like structure is of great application potential in dealing with practically emulsified wastewater.

Rational design of MoS2 nanoflowers-decorated carbon nanofibers with enhanced electronic transmission for boosting capacitive deionization

Capacitive deionization (CDI) has sparked considerable interest for its promising application in handling brackish water. Unfortunately, most traditional carbonaceous materials are still plagued by the limited desalination capacity and sluggish adsorption kinetics with the single adsorption mechanism and irrational pore structure. Herein, we developed a facile and affordable strategy to integrate electrospinning with hydrothermal method to fabricate MoS2 nanoflowers-decorated carbon nanofibers (MoS2/CNF) composite for boosting desalination performance. CNF not only serves as a supportive framework to inhibit the agglomeration of MoS2 nanosheets favoring the full contact with salt solutions, but also typically diminishes the charge transfer resistance of the composite. By taking advantage of the double layer adsorption of CNF and the hierarchically micro-mesoporous structure of MoS2 nanoflowers with large interlayer spacer for salt ions intercalation, the optimized sample MoS2/CNF-1 employed as a cathode for the asymmetric hybrid CDI cell showed an eminent capacity for desalination of 30.9 mg·g−1, an ultrafast rate for desalination of 3.7 mg·g−1·min−1, and an attractive circulation stability for desalination with the capacity reservation remaining at 94.8 % after 30 cycles in the solution of 500 mg·L−1 NaCl at 1.2 V. This research sheds fresh light on the evolution of advanced CDI electrode materials for practical utilization.

Mn Doped MoO3 with Self-Assembled Nanoflowers Structure and Enhanced Gas Sensing Properties to Triethylamine

Increasing quality of life requires low power consumption and reliable gas sensing technology for real-time monitoring of the environment. Herein, based on the principle of ion compensation and charge compensation, Mn-doped MoO3 self-assembled nanoflowers were designed and prepared, and their gas-sensing performance were studied. Benefiting from abundant defective sites and surface chemical state changes, the sensor exhibits superior characteristics for triethylamine detection, including ultrahigh response (436.9), short response time (7 s), small detection limit (1 ppm), and remarkable selectivity. The gas-sensitive mechanism of M-MoO3 was explained from the points of view of charge compensation and ion compensation, and it was proved that the incorporation of Mn into MoO3 was an effective way to improve its gas sensitivity. This work provides a potential strategy for widespread triethylamine detection and provides new ideas for the design of high-performance sensors.

Enhanced photocatalytic degradation of organic dyes by dual heterojunction of ZnO/NiWO4/V2C MXene

Multiphase composite catalysts can be designed for efficient photocatalytic treatment of organic pollutants in wastewater. Herein, the multiphase ZnO/NiWO4/V2C composite catalysts with dual heterojunction and hierarchically assembled nanoflower structures were constructed via a facile two-step hydrothermal and electrostatic self-assembly method. Utilizing NiWO4 and V2C as co-catalysts, these catalysts effectively degraded cationic dyes, methylene blue (MB) and rhodamine B (RhB) under visible light irradiation. The ZnO/NiWO4/V2C catalyst exhibited higher photocatalytic activity than ZnO in the degradation of MB and RhB, with rate constants of 0.0194 min−1 (a 7.43-fold enhancement) and 0.0176 min−1 (a 3.13-fold enhancement). The higher activity can be attributed to the construction of the double heterojunction using NiWO4 and V2C, which can facilitate efficient electron transport, improve charge separation efficiency, and provide more active sites. After four cycles, the ZnO/NiWO4/V2C catalyst still maintained good stability. Consequently, this work can offer a promising approach for environmental pollution treatment.

Unraveling the Effect of Oxygen Vacancy on WO3 Surface for Efficient NO2 Detection at Low Temperature.

Oxygen vacancies (VO) in metal oxide semiconductors play an important role in improving gas-sensing performance of chemiresistive gas sensors. Nonetheless, there is still a lack of clear understanding of the inherent mechanism of the influence of oxygen vacancies on gas sensing due to generally focusing on the concentration of VO. Herein, oxygen vacancies were rationally modulated in WO3 nanoflower structures via an annealing process, resulting in a transformation of VO from neutral (VO0) to a doubly ionized (VO2+) state. Density functional theory (DFT) calculations indicate that VO2+ is significantly more efficient than VO0 for NO2 detection in competition with atmospheric O2. Benefiting from a high concentration of VO2+, the WO3-450 (WO3 annealed at 450 °C) sensor exhibits excellent sensing performance with an ultrahigh sensitivity (3674.1 to 5 ppm NO2), superior selectivity, and long-term stability (one month). Furthermore, the sensor with the wide range of concentration detection not only can detect NO2 gas with parts per million (ppm) but also can detect NO2 with parts per billion (ppb) level concentration, with a high sensibility reaching 2.8 to 25 ppb NO2 and over 100 to 100 ppb NO2. This study elucidates the oxygen vacancy mediated sensing mechanism toward NO2 and provides an effective strategy for the rational design of gas sensors with high sensing performance.

A pH-responsive MOFs@MPN nanocarrier with enhancing antifungal activity for sustainable controlling myclobutanil release

The pH-responsive metal–organic framework (MOF) nanocarriers for sustainable controlled release of pesticides is promising in agricultural production owing to their long duration, high loading efficiency and antimicrobial activity. In this work, myclobutanil (MYC) was loaded into an Ag-based MOF (Ag-TCPP), and modified with a metal-phenolic network (MPN) via in-situ polymerization to construct a pH-responsive nano-delivery system (Ag-TCPP@MYC@MPN). Ag-TCPP@MYC@MPN presented a disordered nanoflower structure and many active sites with potential enhanced loading activity. The cumulative release rates of nanoparticles at pH 4.96, 7.5, and 8.5 were 52.6 %, 62.6 % and 80.0 %, respectively. Hence, Ag-TCPP@MYC@MPN has slow release rate and pH responsiveness. The antifungal activity of Ag-TCPP@MYC@MPN was significantly enhanced, and the bacteriostatic rate reached 81.8 %. This enhancement may be attributed to the synergistic antibacterial effect between tannic acid and Ag+. Safety experiments showed the nanoparticles had no inhibitory effect on the germination of Pakchoi seeds, and the pesticide residues of Ag-TCPP@MYC@MPN did not exceed the food safety standards. This work offers a new potential to develop improved responsive stimulus nanocarriers for sustainable controlled release of MYC.

Enhancement of high-efficiency potassium ion hybrid supercapacitors utilizing oxygen-deficient Co2NiO4@nitrogen-doped carbon nanoflower

Transition metal oxides represent a promising category of pseudocapacitive materials for potassium-ion hybrid supercapacitors (PIHCs) characterized by high energy density. Nevertheless, their utility is hindered by intrinsic low conductivity, restricted electrochemical sites, and notable volume expansion, all of which directly contribute to the degradation of their electrochemical performance, thereby limiting their practical applicability in supercapacitor systems. In this study, we present a facile synthesis approach to fabricate nitrogen-doped carbon-supported oxygen vacancy-rich Co2NiO4 nanoflowers (Ov-Co2NiO4/NC NFs) featuring tunable surface layering and electron distribution. The nanoflower structure augments the contact area between the material and the electrolyte. Density functional theory (DFT) calculations reveal oxygen vacancies could bring an enhanced charge density across the entire Fermi level in Co2NiO4 and expand the interatomic distances between adjacent cobalt and nickel atoms to 3.370 Å. N-doped carbon carriers further accelerate charge transfer, increase the electrostatic energy storage and inhibit the structural collapse of Co2NiO4. These structural modifications serve to improve electrochemical reaction kinetics, augment the binding energy of K+ (−2.87 eV), and mitigate structural variations during K+ storage. In a 6 M KOH electrolyte, Ov-Co2NiO4/NC NF exhibits a specific capacitance of 1104 F g−1 at a current density of 0.5 A g−1, with a remarkable capacitance retention rate of 91.48 % after 6500 cycles. Furthermore, the assembled PIHCs demonstrate an energy density of 47.8 Wh kg−1 and an ultra-high power density of 376 W kg−1, alongside notable cycle stability, retaining 90.13 % of its capacitance after 8000 cycles in a 6 M KOH electrolyte.

Sunlight-promoted CO2 electroreduction with staggered p-n heterojunction by indium-doped bismuth 3D nanoflower structure on oxidized copper foam as self-standing photoelectric cathode over a wide potential window

Exploiting suitable photocathodes to achieve high photocurrent and long-term endurance is still a great challenge in photoelectrocatalytic CO2 reduction (PEC CO2) reactions. Herein, an In-doped Bi2O3 decorated oxidized copper foam (CBIO/CF) self-standing photoelectric cathode is well designed by the self-assembly process without an externally added binder. Via sunlight-promoted strategy, CBIO/CF with a unique 3D hierarchical nanoflower structure displays a superior faradaic efficiency of 90.0 % towards HCOOH over a wide potential window from −0.87 ∼ −1.17 VRHE and reaches 97.8 % at −0.87 VRHE with a partial current density of 14.41 mA cm−2. The in-situ Fourier transform infrared spectroscopy (FTIR) analysis demonstrates the abundant oxygen defects induced by In doping boost CBIO/CF absorbing substantive intermediate species related with formate generations, and porous structure accelerating mass transportation. Moreover, the well-designed staggered p-n heterojunctions of Cu2O and In-doped Bi2O3 on the surface of catalysts favor the generation and separation of electron/hole pairs and contribute to the photocatalytic reduction of CO2 under a bias voltage. This work paves the way for rational regulation of self-supporting photoelectrode for PEC CO2 to HCOOH with suitable conduction band valence bands and high performance and stability.

Photoluminescence Confocal Mapping of a Novel Nd3+/Yb3+: Zn2SiO4 Composite thin film on Si (100) Substrate Utilizing a 980nm Pumping Source.

A fixed Nd3+ and varied Yb3+ ion concentration were incorporated in a Zinc-Silicate (SZNYX) composite solution using ex-situ sol-gel solution to fabricate a novel thin film (TF) on Si (100)-substrate. The upconversion luminescence (UCL) spectra of the thin films were measured under 980nm laser excitation, with the most optimized result for Yb3+ ion concentration of 1.5mol%. Additionally, a 2-D photoluminescence (PL) confocal mapping of the SZNY15-TF material confirmed uniform PL distribution throughout the space under the same excitation wavelength. Structural characterization via XRD revealed the tetragonal Zn2SiO4 nano-crystalline nature of the film at three distinct annealing temperatures. Morphological characterization using the Field-emission scanning electron Microscope (FESEM) coupled with energy dispersion spectrometer (EDS) affirmed the nanoflower structure and the purity of doping purity in the samples, respectively. These findings collectively confirm the promising UCL properties of the SZNYX-TF samples, suggesting potential applications in photonic.